Language: clone() on enum unit cases — Error exception (Zend zend_clones.c parity) #3554

Category

language

Problem

Cloning an enum case must throw Error in Zend; this compiler throws LogicException: clone requires an object.

<?php
enum E { case A; }
try {
    clone E::A;
} catch (Throwable $e) {
    echo get_class($e), "\n";
}

Backed enum cases share the same restriction.

php-src reference

• php/php-src Zend/zend_clones.c — zend_clone_obj enum guard
• php/php-src Zend/zend_enum.c

Repro

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php repro.php'
# LogicException

php repro.php
# Error

Expected behavior

• clone SomeEnum::Case → Error with Zend-aligned message (Cannot clone enum case, or equivalent)
• Distinct from readonly-object clone rules (Language: clone() on readonly objects — deep copy + readonly property guards (Zend zend_clones.c parity) #3430)

Implementation hints

• VM clone opcode / builtin: detect enum case objects before generic object clone
• Use Error (not LogicException) via VM exception class table

Acceptance

• test/compliance/cases/language/clone_enum_case_error.phpt